Regular Expression-Learn from matching North American phone numbers and email addresses

The general North American phone number format is:

999-999-9999

Or 999x999x9999 (X represents any character)

Match with character groups:

[0-9][0-9][0-9]-[0-9][0-9][0-9]-[0-9][0-9][0-9][0-9]

Abbreviated character group:

\d\d\d-\d\d\d-\d\d\d\d

Including the selected characters:

^(\(\d{3}\)|^\d{3}[.-]?)?\d{3}[.-]?\d{4}$

The first ^ indicates that the phone number will appear at the starting position of a line.

Left brackets {start character of the capture group

\ (Represents the left bracket itself (Escape Character)

\ D matches a digit

The {3} After \ D is a quantizer, indicating that it matches three digits.

\} Match the right brace itself (Escape Character)

| Indicates selection, that is, multiple options are selected

^ Match the starting position of a row

\ D matches a digit

{3} indicates the quantifiers matching three digits.

[.-]? Match an optional dot or hyphen

The ending character of the capture group.

? Indicates that the group is optional, that is, the prefix in the group is optional.

\ D matches a digit

{3} indicates the quantifiers matching three digits.

[.-]? Match another optional dot or hyphen

\ D matches a digit

{4} is a quantizer that matches four digits.

$ Match the end position of a row

 

 

Next we will talk about a regular expression that matches the North American phone number:

^\(?(?:\d{3})\)?[.-]?(?\d{3})[.-]?(?:\d{4})$

Where (? : XXXX) indicates a non-capturing group. A non-capturing group does not store its content in the memory, resulting in higher performance.

 

Match the regular expression of the email address:

^([\w-.!#$%&'*-+=/?^_{|}~]+)@((?:\w+\.)+)(?:[a-zA-Z]{2,4})$

 

 

Predefined character set:

 

\ W matches a word character, equivalent to [a-zA-Z0-9]

\ W matches a non-word character [\ ^ \ W]

\ D indicates matching a number [0-9]

\ D matches a non-digit [^ \ D]

\ S matches a blank character [<space> \ t \ r \ n \ f \ v]

\ S matches a non-blank character [^ \ s]

 

Quantifiers:

 

* Match the first character 0 or unlimited times

+ Match the first character once or infinitely

? Match the first character 0 or 1 time

{M} matches the previous character m times

{M, n} matches the previous character M-N times

 

 

Boundary

 

^ Match the start of a string. In multiline mode, match the beginning of each line.

$ Match the end of a string. In multiline mode, China matches the end of each row.

\ A only matches the start of a string

\ Z only matches the end of the string

\ B matches \ W and \ W

\ B match [^ \ B]

 

 

[] Character Set

{} Generally refers to quantifiers.

() Indicates a group.

(? :) Generally, it indicates a non-capturing group.